This invention relates to flow control devices and, more particularly, to a compact gas flow control valve of unusual simplicity and economy.
The invention is particularly concerned with controlling the flow of oxygen from a source of regulated pressure at a desired, constant flow rate as dictated by medical requirements, such as for emergency treatment, and for hospital, clinical and other uses, including domestic therapeutic personal usage as for treatment of chronic conditions. In these different kinds of usages, it may be required to deliver oxygen at a flow rate which may vary from very little, such as as low as 0.25 liters per minute, up to approximately 15 liters per minute. Hence it is desired to allow ready preselection of a desired flow rate.
Medical professionals in insititutions or other users of such equipment may have different preferences as to the minimum and maximum volumetric flow rates which such apparatus should provide. Further, different users are expected to have different preferences as to the available sequence of flow rates.
For example, one user may prefer a control sequence of 0.5, 0.75, 1, 1.5, 2, 3.5, etc., liters per minute; whereas another user may prefer a sequence of 1, 2, 4, 6, 8, etc., liters per minute, so that the design of such apparatus is rendered difficult for all intended modes of usage. Although the use of vernier controls allowing infinite adjustmentsof flow rate has been proposed, in medical usage, it is preferred to be able to positively and rapidly allow selection only according to such a preferred sequence, thereby assuring rapid, error-reducing selection, as required in prompt emergency treatment and with only definite discreet control positions being available so as to preclude inaccurate settings in operative positions, and to obviate close visual monitoring of selections and flow rates.
In, coassigned Phlipot et al U.S. application Ser. No. 537,653, filed Sept. 30, 1983, now U.S. Pat. No. 4,572,477, a regulated gas flow control valve is disclosed for overcoming such problems and providing for selection of a precalibrated flow rate of oxygen from a constant delivery pressure according to a preferred schedule of delivery rates. Such gas flow control valve utilized a rotor having a plurality of orifice inserts spaced at arcuate intervals around the rotor, each insert being individually precalibrated to provide a fixed flow rate, and each insert being positioned within a respective recess of the rotor. While this arrangement provides extreme accuracy as well as the capability of conveniently establishing a preselected schedule of different flow rates to be selected by rotation of the rotor, the process of manufacturing and calibrating the individual orifice inserts is more time consuming and expensive than desired.
Accordingly, it is an object of the present invention to provide a compact gas control valve of improved economy and simplicity, as well as being much more easily manufactured and eliminating or reducing the time heretofore required for calibration of gas flow rates provided by the valve.
It is a further object of the invention to provide such an improved flow control valve which is particularly intended for controlling the flow control of oxygen delivered from a source thereof, such as from a high pressure oxygen cylinder.
It is also an object of the invention to provide such a gas flow control valve which allows definite, positive selection only of a desired one of a plurality of available flow rates, precluding inaccurate or indefinite settings, in operative selector positions, and eliminating need for close visual monitoring or the control valve or flow rates provided thereby.
It is additionally an object of the present invention to provide such a gas flow control valve which allows and facilitates rapid changing of a flow control member to establish a different flow control sequence of available flow control rates, thus allowing ready selection of a preferred schedule of flow, i.e., delivery rates.
Among other objects of the present invention are the provision of such a gas flow control valve which is of extremely compact, streamlined and efficient construction, being both reliable and long lasting in usage as well as relatively light in weight.
Briefly, a gas flow control valve of the invention includes a single valve body having within it a valve member in the form of a rotor which carries a very thin flow control plate having orifices of a precise diameter provided therein. The orifices may be provided by one of various processes, including mechanical drilling, laser drilling, piercing, punching or selective etching.
Other objects and features will be in part apparent and in part pointed out hereinbelow.